contrib/editmerge

py3: partially fix pager spawning on Windows

Previously, spinning up the pager crashed because the command and environment
was in bytes.  (See also 543a788eea2d.)  Now it aborts with an invalid handle:

    $ HGMODULEPOLICY=py py -3 ../hg --traceback --config extensions.evolve=!
    Traceback (most recent call last):
    File "c:\Users\Matt\projects\hg\mercurial\ui.py", line 967, in _write
      self.fout.write(''.join(msgs))
    File "c:\Users\Matt\projects\hg\mercurial\windows.py", line 173, in write
      self.fp.write(s[start:end])
    OSError: [WinError 6] The handle is invalid

    During handling of the above exception, another exception occurred:

    Traceback (most recent call last):
      File "c:\Users\Matt\projects\hg\mercurial\scmutil.py", line 164, in callcatch
        return func()
      File "c:\Users\Matt\projects\hg\mercurial\dispatch.py", line 350, in _runcatchfunc
        return _dispatch(req)
      File "c:\Users\Matt\projects\hg\mercurial\dispatch.py", line 930, in _dispatch
        return commands.help_(ui, 'shortlist')
      File "c:\Users\Matt\projects\hg\mercurial\commands.py", line 2930, in help_
        ui.write(formatted)
      File "c:\Users\Matt\projects\hg\mercurial\ui.py", line 948, in write
        self._writenobuf(*args, **opts)
      File "c:\Users\Matt\projects\hg\mercurial\ui.py", line 960, in _writenobuf
        self._write(*msgs, **opts)
      File "c:\Users\Matt\projects\hg\mercurial\ui.py", line 969, in _write
        raise error.StdioError(err)
    mercurial.error.StdioError: [Errno 9] The handle is invalid
    abort: The handle is invalid

The interesting bit here is that the abort message is marked with ANSI color,
but the OSError is not.

#!/usr/bin/env bash
# A simple script for opening merge conflicts in the editor.
# Use the following Mercurial settings to enable it.
#
# [ui]
# merge = editmerge
#
# [merge-tools]
# editmerge.args=$output
# editmerge.check=changed
# editmerge.premerge=keep

FILE="$1"

getlines() {
  grep -n "^<<<<<<" "$FILE" | cut -f1 -d:
}

# editor preference loosely based on https://mercurial-scm.org/wiki/editor
# hg showconfig is at the bottom though, since it's slow to run (0.15 seconds)
ED="$HGEDITOR"
if [ "$ED" = "" ] ; then
  ED="$VISUAL"
fi
if [ "$ED" = "" ] ; then
  ED="$EDITOR"
fi
if [ "$ED" = "" ] ; then
  ED="$(hg showconfig ui.editor)"
fi
if [ "$ED" = "" ] ; then
  echo "merge failed - unable to find editor"
  exit 1
fi

if [ "$ED" = "emacs" ] || [ "$ED" = "nano" ] || [ "$ED" = "vim" ] ; then
  FIRSTLINE="$(getlines | head -n 1)"
  PREVIOUSLINE=""

  # open the editor to the first conflict until there are no more
  # or the user stops editing the file
  while [ ! "$FIRSTLINE" = "" ] && [ ! "$FIRSTLINE" = "$PREVIOUSLINE" ] ; do
    $ED "+$FIRSTLINE" "$FILE"
    PREVIOUSLINE="$FIRSTLINE"
    FIRSTLINE="$(getlines | head -n 1)"
  done
else
  $ED "$FILE"
fi

# get the line numbers of the remaining conflicts
CONFLICTS="$(getlines | sed ':a;N;$!ba;s/\n/, /g')"
if [ ! "$CONFLICTS" = "" ] ; then
  echo "merge failed - resolve the conflicts (line $CONFLICTS) then use 'hg resolve --mark'"
  exit 1
fi

exit 0